Influence of Nb Doping on Electrochemical Performance of Nanostructured Cation Disordered LiNiTiNbO₂ Composites Cathode for Li-Ion Batteries.

Li-excess cation-disordered rock-salts LiNiTiNbO₂ ( = 0, 5, 10, 15, 20) were synthesized in this study, and effects of Nb doping on their electrochemical performance were also investigated. X-ray diffraction (XRD) indicated that the rock-salt structure was maintained, but with lower crystallization. The scanning electron microscopy (SEM) displayed Nb-doped samples' morphology and particles were uniformly distributed within 100 nm. The transmission electron microscopy (TEM) analysis also confirmed that these Nb-doped samples still maintained the cationdisordered rock-salt structure. Charge-discharge test showed that the electrochemical performance was greatly improved after Nb-doping. The LiNiTiNbO₂ sample delivered highest capacity of up to 226.5 mAh·g, at 20 mA·g density. Moreover, the sample still delivered 130 mAh·g capacity of even 400 mA·g density. This result indicates that the Nb-doping improved the cycling performance and rate capacity. In addition, electrochemical impedance spectroscopy (EIS) test showed that the Nb-doping further enhanced mobility of Li-ions when forming the 0-TM channel.